1. Field of the Invention
The present invention relates to a radio terminal that utilizes an intermittent transmission-reception method, a radio synchronization system that has no base station and that is applied to a telecommunications system including a plurality of such radio terminals, and a medium recording the program therefor.
2. Description of the Related Art
Japanese Patent Laid-Open Hei 10(1998)-51376 discloses a synchronization system and method for synchronizing the transmission timing of a plurality of mobile stations to that of a telecommunications system. According to this prior art, a mobile station can be synchronized to a telecommunications system without receiving any synchronization control from a fixed station. Specifically, a mobile station attempting to participate in a telecommunications network detects with its monitor portion the cycle of a slot in use located before the slot used by itself. Thereafter, using the detected cycle, the control portion of the mobile station calculates the deviation Δt of the transmission timing of itself from the slot timing of the telecommunications network. Thereafter, control portion 19 of the mobile terminal adjusts the transmission timing of itself by deviation Δt, thereby synchronizing itself to the telecommunications network.
The system according to the prior art above has the following characteristics.
(1) A method is provided of how a terminal participates in a network where quasi-synchronization is established;
(2) The prior art does not directly receive synchronization control from a fixed station, but detects the timing from a terminal participating in the network, so it indirectly uses the timing from a fixed station. Therefore, the system according to the prior art above requires a reference station for the timing.
(3) The prior art determines the access timing of itself by searching for an unused slot.
As the prior art above indirectly uses the timing from a fixed station, it cannot be applied to a radio communications system structured only of a plurality of mobile terminals.
The present invention aims at solving such problem by providing a radio terminal, a radio synchronization system and a medium recording a program therefor, used in a radio communications system formed only of a plurality of mobile terminals, that allows synchronization between all terminals.